An airplane pilot fell to the ground after jumping from an aircraft without his parachute opening. He lands in a snowbank, creating a crater 2.1 m deep, but survived with only minor injuries.  Assuming the pilot’s mass was 68 kg and his terminal velocity was 35 m/s (the velocity at the point he stopped accelerating on his way down), what is: a) the average force exerted on him by the snow in bringing him to rest?  b) the work done by the snow?

A 7.80-g bullet moving at 690 m/s penetrates a tree trunk to a depth of 5.10 cm. (a) Use work and energy considerations to find the average frictional force that stops the bullet.N(b) Assuming the frictional force is constant, determine how much time elapses between the moment the bullet enters the tree and the moment it stops moving.s

You and your bicycle have combined mass 80.0 kg. When you reach the base of a bridge, you are traveling along the road at 5.00 m>s (Fig. ). At the top of the bridge, you have climbed a vertical distance of 5.20 m and slowed to 1.50 m/s. Ignore work done by friction and any inefficiency in the bike or your legs. (a) What is the total work done on you and your bicycle when you go from the base to the top of the bridge? (b) How much work have you done with the force you apply to the pedals?

A 7.80-g bullet moving at 520 m/s penetrates a tree trunk to a depth of 6.30 cm. Answer parts a-b.

(a) A block with a mass m is pulled along a horizontal surface for a distance x by a constant force F at an angle e with respect to the horizontal. The coefficient of kinetic friction between block and table is u. Is the force exerted by friction equal to u, mg? If not, what is the force exerted by friction? (Assume 0 is measured above the horizontal.) This answer has not been graded yet. (b) How much work is done by the friction force and by F? (Don't forget the signs. Use the following as necessary: F for the magnitude of F, g, m, x, 0 and u,) WE = (c) Identify all the forces that do no work on the block. (Select all that apply.) O friction f OF Cos(e) OF sin(0) O mE (d) Let m = 2.00 kg, x = 4.50 m, 0 = 3.7°, F = 14.5 N, and u, = 0.400, and find the answers to parts (a) and (b). (Include appropriate signs.) We = W =

A 60 Nt force is exerted on a 5 kg box at an angle of 60° above the horizontal.  (a)  What is the work done by the 60 Nt force on the box if the box moves a distance of 2 m across the floor? (b)  What is the work done by the normal force?:  (c)  If the box moves at a constant speed, what is the work done by friction on the box?:  (d)  What is the work done by gravity on the box?  (e)  What is the total work done by all of the forces on the box?

A tank has the shape of an inverted right circular cone with height 9m and radius 18m. It is filled with 5m of hot chocolate. Assume that the density of the hot chocolate is 1450kg/m^3 and g=9.8m/s^2.Find the work required to empty the tank by pumping the hot chocolate over the top of the tank.Work =  Joules.

A horizontal force, acts on an 8N box. The box moves 12 m horizontally at a constant speed. The coefficient of kinetic friction is 0.25. Determine the work done by the horizontal force.

A 7.80-g bullet moving at 470 m/s penetrates a tree trunk to a depth of 5.60 cm.(a) Use work and energy considerations to find the average frictional force that stops the bullet.N (b) Assuming the friction force is constant, determine how much time elapses between the moment the bullet enters the tree and the moment it stops moving.s

A 58.1-kg skateboarder starts out with a speed of 2.03 m/s. He does 108 J of work on himself by pushing with his feet against the ground. In addition, friction does -243 J of work on him. In both cases, the forces doing the work are non-conservative. The final speed of the skateboarder is 7.89 m/s. (a) Calculate the change (PEf - PE0) in the gravitational potential energy. (b) How much has the vertical height of the skater changed? Give the absolute value.